ATV

ATV-3 ‘Edoardo Amaldi’ reaches its destination

29 March 2012

Perfect docking with the ISS

The most intelligent space robot in the world has docked autonomously with the International Space Station

After a six-day flight, the ATV-3 ‘Edoardo Amaldi’, the third unmanned supply vehicle designed and built by Airbus Defence and Space for the European Space Agency (ESA), has executed a perfect manoeuvre to dock autonomously with the International Space Station (ISS). It is the biggest, most complex spacecraft ever developed and built in Europe.

The ATV-3 docked exactly as planned with the Russian Zvezda module, achieving a docking accuracy of better than 10 centimetres. The entire docking sequence took place flawlessly.

The ATV-3 ‘Edoardo Amaldi’, which was launched on 23 March by a specially adapted version of the Ariane 5 rocket, has taken 6.6 metric tonnes of freight for the space station, including four metric tonnes of fuel, water and gases.

The cargo contains everything that the on-board crew of the ISS need for living and working in space – food, clothing, toiletries, medical supplies, spare parts, tools and experiments. The ATV additionally carries fuel to be used in re-boost manoeuvres for regular orbit and attitude adjustment of the ISS.

Perfect rendezvous in space

The ATV-3’s automated rendezvous and docking phase began at some 30 kilometres distance from and five kilometres below the ISS, when the ATV systems precisely established its relative position and velocity with respect to the ISS. The first automated rendezvous manoeuvres, computed and executed by the ATV on its own, brought the vehicle to a ‘hold’ position 3,500 metres behind the ISS. After authorisation from the ground, the ATV proceeded automatically to the next hold point, at a distance of 250 metres. At this point, the ATV system switched to relative guidance, navigation and control mode (GNC) using its optical sensors to lock onto the ISS. After authorisation by the ATV control centre, the ATV continued its approach up to the hold position at 20 metres from the ISS; it then began to also control its attitude in relation to that of the ISS, in the approach that took it to 12 metres. Following a last ‘go’ from the ATV control centre, jointly agreed with the ISS crew and ISS ground control centres, ‘Edoardo Amaldi’ covered the last few meters to the ISS’ docking port at a relative maximum speed of not more than 10 centimetres per second.

The axis of ATV’s extended docking probe, the head of which has a diameter of about 15 centimetre, was brought into contact at 22:31 GMT on 28 March with the docking port of the Russian Zvezda module with an accuracy of better than 10 centimetres. The docking port is a passive cone which has a diameter of 90 centimetres. The first contact made, the ATV docking head locked with ISS docking port. ATV then executed an automated sequence that set-up all electrical, mechanical and fluid connections with the ISS.

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